Configurable Pre-Emphasis Filter for Analog Distortion Compensation
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Solution Overview
Problem
Conventional transmission circuitry experiences distortion due to analog components between the digital predistortion (DPD) component and the power amplifier (PA), leading to noise and transmission errors, which existing solutions like DPD components cannot fully mitigate.
Innovation Solution
A configurable pre-emphasis filter (PEF) component is introduced to modify the DPD output signal by compensating for the frequency response of analog components, such as filters and mixers, to offset their distorting effects, thereby ensuring a more linear relationship between the source and amplified signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DPD component is used to compensate for power amplifier non-linearity, then linear relationship between source signal and amplified output signal is improved, but distortion from analog components between DPD and PA is not fully mitigated
Solution Approach 1:
The pre-emphasis filter applies preliminary compensation to the digital signal before it reaches the analog components. By calculating and applying the inverse frequency response of the analog components in the digital domain, the signal is pre-adjusted to counteract the distortion that will be introduced by the analog filter and mixer, thereby improving overall linearity.
Solution Approach 2:
The pre-emphasis filter acts as an intermediary component between the DPD component and the analog components. It processes the DPD output signal digitally to compensate for analog component characteristics, serving as a bridge that translates analog component requirements into digital signal adjustments without requiring direct modification of the analog components themselves.
2Adaptability or versatility
If analog components (filter, mixer) are used in transmission circuitry, then signal processing functionality is improved, but frequency response distortion is introduced
Solution Approach 1:
The system uses measured frequency response data from the analog components to generate compensation coefficients for the pre-emphasis filter. By measuring the actual frequency response of the analog filter and mixer, and using this information to adjust the digital signal accordingly, the system creates a feedback loop that compensates for the analog components' distortion characteristics.
Solution Approach 2:
The pre-emphasis filter dynamically adjusts signal parameters (amplitude and phase) across different frequency components based on the measured frequency response of the analog components. By changing the signal parameters in the digital domain to counteract the analog component distortion, the system maintains frequency response accuracy while preserving the necessary signal processing functionality.
Data Source
AI summary
A configurable pre-emphasis filter component may be configured based upon measured frequency response (e.g., filter effect) associated with at least one analog filter positioned between a digital predistortion component and a power amplification component of a transmission circuitry. The frequency response may be measured using a calibration signal sent via the transmission circuitry, a loopback circuit, and a reception circuitry. Calibration circuitry may be used with one or more loopback circuits to measure the frequency response of various analog components of the transmission circuitry. The calibration circuitry may also include logic to determine a configuration for the PEF component based upon the measured frequency response.